Media grid view not working

Hello,

It’s been a couple of weeks that media is not loading in grid view. The gray circle keeps spinning infinitely. This means that I am not able to set any featured image to a post (as there only grid view exists). I don’t know what changed… I have tried deactivating plugins, using a base theme, deleting code from functions.php… everything that I’ve seen on the internet, and nothing worked. I am completely lost, I need help. Any idea? WordPress version is 4.9.5.